public class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode node = new ListNode(0);
        ListNode cur = node;
        while(list1 != null && list2 != null){
            if(list1.val < list2.val){
                cur.next = list1;
                list1 = list1.next;
            } else {
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;
        }
        if(list1 != null){
            cur.next = list1;
        } else if(list2 != null){
            cur.next = list2;
        }
        node = node.next;

        return node;

    }

}
class ListNode {
    int val;
    ListNode next;

    ListNode() {
    }

    ListNode(int val) {
        this.val = val;
    }

    ListNode(int val, ListNode next) {
        this.val = val;
        this.next = next;
    }
}
